Detectability of Foreign Body Materials Using X-ray, Computed Tomography and Magnetic Resonance Imaging: A Phantom Study.

Purpose: To evaluate the effectiveness of plain radiography (X-ray. XR), computed tomography (CT) and magnetic resonance imaging (MR) in visualising commonly seen foreign bodies. A special focus was put on objects relevant to head and neck surgery. Method: Thirty-four commonly encountered objects of different compositions including wood, plastic, and glass were embedded in a gelatin gel phantom and imaged using XR, CT and MR. The success rates of radiologists in detecting and correctly identifying the foreign objects were evaluated. Subjective visibility was rated on a 4-point Likert scale. Objective visibility was analysed using region of interest-based contrast for CT. Results: Sensitivity in foreign bodies detection was highest in MR (97.1 %) followed by CT (86.0 %) and x-ray (61.8 %). Success rates for the correct identification of the objects and material types were highest in MR (33.3 % and 39.2 %, respectively) followed by CT (25.5 % for both) and XR (16.7 % and 15.7 %). Overall, subjective visibility was rated higher in CT and MR imaging ("good visibility"), as compared to XR ("poor visibility"). Interreader agreement was high across modalities (Kendall's W = 0.935, 0.834 and 0.794 for XR, MR and CT, respectively). Conclusions: Detection and identification of non-ferromagnetic objects was most successful in MR followed by CT imaging in this experimental setup.